The present invention pertains to a hand pump for use with a sphygmomanometer. More particularly, the invention pertains to an inflation bulb with an intake valve permanently secured therein.
Sphygmomanometers are used to measure an individual's blood pressure. A sphygmomanometer includes a hand pump connected to a pressure control valve which is further connected to a pressure cuff through a piece of tubing. The tubing also connects the pressure cuff to a gauge for measuring pressure within the pressure cuff. The pressure control valve includes a thumb screw that acts as a release valve for air at or beyond the pressure control valve within the system.
The sphygmomanometer is used to measure blood pressure by first wrapping the pressure cuff typically around a patient's arm. Next, the pressure cuff is inflated by compressing the hand pump which forces air into the cuff. The thumb screw on the pressure control valve controls the flow of air into or from the pressure cuff. When the thumb screw is closed, air is forced from the hand pump, through the pressure control valve, and into the pressure cuff via the tubing. If the thumb screw is open, the pressure control valve releases air either from within the pressure cuff or as the air is pumped through the pressure control valve by the hand pump.
In order for the hand pump to function properly, it must be compressible and maintain air flow in only one direction. To meet these requirements, the hand pump generally includes an inflation bulb and an intake valve. The inflation bulb is generally constructed out of a rubber type of material which is typically black in color and has an oval shape that includes an inlet and an outlet into the bulb's hollow center. The hollow center of the inflation bulb acts as a reservoir for storing air that will be pumped into the pressure cuff for inflation.
The intake valve is normally inserted into the inlet of the inflation bulb to allow air flow in only one direction. The intake valve is positioned to allow air to flow into the hollow center of the inflation bulb from the surrounding external environment. The intake valve being uni-directional prevents air from exiting the inlet of the inflation bulb once the air is contained within the hollow center. The intake valve operates by allowing air to flow into the inflation bulb when a pressure differential exists across the intake valve at the inlet of the inflation bulb. The pressure differential is created between the hollow center of the inflation bulb and the surrounding external environment. The pressure differential exists when the pressure within the inflation bulb is less than the pressure of the surrounding external environment, such as after the inflation bulb has been compressed. As a result of the pressure differential, the intake valve allows air to flow from the surrounding external environment through the intake valve and into the hollow center of the inflation bulb. This occurs when the inflation bulb is released from a compressed state. Upon equalizing the pressure differential, the intake valve prevents further air flow either into or out of the inlet of the inflation bulb.
Once the center of the inflation bulb is filled with air, the inflation bulb can be compressed to force the air out through the outlet of the inflation bulb, through the pressure control valve, and into the tubing to inflate the pressure cuff. During the compression of the inflation bulb, the intake valve prevents air from escaping through the inlet, thus forcing the air out through the outlet. This cycle is repeated until the pressure cuff is inflated to a desired level.
The appearance of the standard hand pump--primarily the black, rubber, oval shaped inflation bulb--is typically unfamiliar and unappealing to children. When medical personnel attempt to take a child's blood pressure with the standard band pump, it generally creates anxiety in the child. The child's anxiety makes the measurement more difficult and less accurate, which can lead to an increased potential for misdiagnosis. To calm the child's fear and anxiety of the instrument, medical personnel may allow the child to play with the hand pump in the hope that the child may associate with the instrument and overcome their fear. However, the standard hand pump is not safe for young children to handle. In particular, the intake valve at the inlet of the standard type of inflation bulb can be easily removed or unseated. Once removed from the inlet of the inflation bulb, the intake valve is small and creates a choking hazard, especially for young children.